Optical receiver with photodiode disposed directly on a planar lightwave circuit

Abstract

An optical receiver may include a planar lightwave circuit with an optical path and a tapered reflection surface to direct an optical beam toward a top surface of the planar lightwave circuit. The optical receiver may include a photodiode disposed onto the top surface of the planar lightwave circuit such that a receive portion of the photodiode is aligned to the optical path, wherein a gap between the photodiode and the planar lightwave circuit is less than 5 microns.

What is claimed is: 
     
       1. An optical receiver, comprising:
 a planar lightwave circuit with an optical path and a tapered reflection surface to direct an optical beam toward a top surface of the planar lightwave circuit; and 
 a photodiode disposed onto the top surface of the planar lightwave circuit such that a receive portion of the photodiode is aligned to the optical path,
 wherein a gap between the photodiode and the planar lightwave circuit is less than 5 microns, and 
 wherein a bottom surface of the photodiode extends beyond an edge of the planar lightwave circuit where the top surface of the planar lightwave circuit and the tapered reflection surface meet. 
 
 
     
     
       2. The optical receiver of  claim 1 , further comprising:
 a matching block with a tapered surface matched to the tapered reflection surface to structurally support the tapered reflection surface. 
 
     
     
       3. The optical receiver of  claim 2 , wherein the matching block is bonded to the tapered reflection surface of the planar lightwave circuit. 
     
     
       4. The optical receiver of  claim 2 , wherein a first coefficient of thermal expansion (CTE) of the matching block is within a threshold amount of a second CTE of the planar lightwave circuit. 
     
     
       5. The optical receiver of  claim 2 , wherein a surface of the matching block and the top surface of the planar lightwave circuit are aligned to within a tolerance of less than 1 micron. 
     
     
       6. The optical receiver of  claim 1 , wherein the photodiode is passively aligned to the planar lightwave circuit. 
     
     
       7. The optical receiver of  claim 1 , wherein the gap between the photodiode and the planar lightwave circuit is less than 3 microns. 
     
     
       8. The optical receiver of  claim 1 , wherein the photodiode is die bonded to the planar lightwave circuit. 
     
     
       9. A method, comprising:
 passively aligning, by a device, a photodiode to an output, of an optical path of a planar lightwave circuit, on a top surface of the planar lightwave circuit such that a receive portion of the photodiode is aligned to the output of the optical path of the planar lightwave circuit,
 wherein the optical path of the planar lightwave circuit extends along the top surface of the planar lightwave circuit and is directed by a tapered reflection surface of the planar lightwave circuit toward the output on the top surface of the planar lightwave circuit; and 
 
 bonding, by the device, the photodiode to the top surface of the planar lightwave circuit based on passively aligning the photodiode to the output of the optical path,
 a bottom surface of the photodiode extending beyond an edge of the planar lightwave circuit where the top surface of the planar lightwave circuit and the tapered reflection surface meet. 
 
 
     
     
       10. The method of  claim 9 , further comprising:
 identifying a set of fiducial markers on the top surface of the planar lightwave circuit,
 wherein the set of fiducial markers correspond to the output of the planar lightwave circuit; and 
 
 wherein passively aligning the photodiode to the planar lightwave circuit comprises:
 passively aligning the photodiode to the set of fiducial markers. 
 
 
     
     
       11. The method of  claim 10 , wherein passively aligning the photodiode to the set of fiducial markers comprises:
 passively aligning the photodiode with respect to a first degree of freedom and a second degree of freedom using the set of fiducial markers; and 
 passively aligning the photodiode with respect to a third degree of freedom using a force detector. 
 
     
     
       12. The method of  claim 9 , wherein passively aligning the photodiode comprises:
 passively aligning the photodiode with a gap of less than 5 microns. 
 
     
     
       13. The method of  claim 9 , wherein bonding the photodiode comprises:
 flip-chip bonding the photodiode to the top surface of the planar lightwave circuit. 
 
     
     
       14. The method of  claim 9 , wherein bonding the photodiode comprises:
 soldering the photodiode to at least one of the planar lightwave circuit, a substrate, or a transimpedance amplifier and clock and data recovery module. 
 
     
     
       15. An optical module, comprising:
 a planar lightwave circuit with an optical path and a tapered reflection surface to direct an optical beam toward a top surface of the planar lightwave circuit; 
 a matching block with a tapered surface matched to the tapered reflection surface to structurally support the tapered reflection surface; 
 a photodiode disposed onto the top surface of the planar lightwave circuit such that a receive portion of the photodiode is aligned to the optical path,
 wherein a gap between the photodiode and the planar lightwave circuit is less than 1 microns, and 
 wherein a bottom surface of the photodiode extends beyond an edge of the planar lightwave circuit where the top surface of the planar lightwave circuit and the tapered reflection surface meet; and 
 
 a transimpedance amplifier and clock and data recovery module connected to the photodiode. 
 
     
     
       16. The optical module of  claim 15 , wherein the transimpedance amplifier and clock and data recovery module is bonded to the top surface of the planar lightwave circuit or the matching block. 
     
     
       17. The optical module of  claim 15 , wherein the tapered reflection surface is metal coated. 
     
     
       18. The optical module of  claim 15 , wherein the photodiode is flip-chip bonded to the planar lightwave circuit using a solder bond. 
     
     
       19. The optical module of  claim 15 , wherein the transimpedance amplifier and clock and data recovery module forms the matching block. 
     
     
       20. The optical module of  claim 15 , wherein the photodiode is passively aligned to the planar lightwave circuit.